* Re: [PATCH] xen-netback: correctly check failed allocation
2015-10-16 9:05 ` Wei Liu
@ 2015-10-16 9:28 ` Wei Liu
2015-10-16 9:28 ` Wei Liu
` (2 subsequent siblings)
3 siblings, 0 replies; 11+ messages in thread
From: Wei Liu @ 2015-10-16 9:28 UTC (permalink / raw)
To: Insu Yun
Cc: Ian Campbell, Wei Liu, xen-devel, netdev, linux-kernel,
Taesoo Kim, Yeongjin Jang, Yun, Insu
On Fri, Oct 16, 2015 at 10:05:21AM +0100, Wei Liu wrote:
> On Thu, Oct 15, 2015 at 02:02:47PM -0400, Insu Yun wrote:
> > I changed patch with valid format.
> >
> > On Thu, Oct 15, 2015 at 2:02 PM, Insu Yun <wuninsu@gmail.com> wrote:
> >
> > > Since vzalloc can be failed in memory pressure,
> > > writes -ENOMEM to xenstore to indicate error.
> > >
> > > Signed-off-by: Insu Yun <wuninsu@gmail.com>
> > > ---
> > > drivers/net/xen-netback/xenbus.c | 6 ++++++
> > > 1 file changed, 6 insertions(+)
> > >
> > > diff --git a/drivers/net/xen-netback/xenbus.c
> > > b/drivers/net/xen-netback/xenbus.c
> > > index 929a6e7..56ebd82 100644
> > > --- a/drivers/net/xen-netback/xenbus.c
> > > +++ b/drivers/net/xen-netback/xenbus.c
> > > @@ -788,6 +788,12 @@ static void connect(struct backend_info *be)
> > > /* Use the number of queues requested by the frontend */
> > > be->vif->queues = vzalloc(requested_num_queues *
> > > sizeof(struct xenvif_queue));
> > > + if (!be->vif->queues) {
> > > + xenbus_dev_fatal(dev, -ENOMEM,
> > > + "allocating queues");
> > > + return;
> > >
> >
> > I didn't use goto err, because another error handling is not required
> >
>
> It's recommended in kernel coding style to use "goto" style error
> handling. I personally prefer that to arbitrary return in function body,
> too.
>
> It's not a matter of whether another error handling is required or not,
> it's about cleaner code that is easy to reason about and consistent
> coding style.
>
> The existing code is not perfect, but that doesn't mean we should follow
> bad example.
And to be clear, I don't want to block this patch just because of this
coding style thing. It's still an improvement and fix a real problem.
So:
Acked-by: Wei Liu <wei.liu2@citrix.com>
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [PATCH] xen-netback: correctly check failed allocation
2015-10-16 9:05 ` Wei Liu
2015-10-16 9:28 ` Wei Liu
@ 2015-10-16 9:28 ` Wei Liu
2015-10-16 9:40 ` [Xen-devel] " David Vrabel
2015-10-16 9:40 ` David Vrabel
3 siblings, 0 replies; 11+ messages in thread
From: Wei Liu @ 2015-10-16 9:28 UTC (permalink / raw)
To: Insu Yun
Cc: Yeongjin Jang, Taesoo Kim, Wei Liu, Ian Campbell, netdev,
Yun, Insu, linux-kernel, xen-devel
On Fri, Oct 16, 2015 at 10:05:21AM +0100, Wei Liu wrote:
> On Thu, Oct 15, 2015 at 02:02:47PM -0400, Insu Yun wrote:
> > I changed patch with valid format.
> >
> > On Thu, Oct 15, 2015 at 2:02 PM, Insu Yun <wuninsu@gmail.com> wrote:
> >
> > > Since vzalloc can be failed in memory pressure,
> > > writes -ENOMEM to xenstore to indicate error.
> > >
> > > Signed-off-by: Insu Yun <wuninsu@gmail.com>
> > > ---
> > > drivers/net/xen-netback/xenbus.c | 6 ++++++
> > > 1 file changed, 6 insertions(+)
> > >
> > > diff --git a/drivers/net/xen-netback/xenbus.c
> > > b/drivers/net/xen-netback/xenbus.c
> > > index 929a6e7..56ebd82 100644
> > > --- a/drivers/net/xen-netback/xenbus.c
> > > +++ b/drivers/net/xen-netback/xenbus.c
> > > @@ -788,6 +788,12 @@ static void connect(struct backend_info *be)
> > > /* Use the number of queues requested by the frontend */
> > > be->vif->queues = vzalloc(requested_num_queues *
> > > sizeof(struct xenvif_queue));
> > > + if (!be->vif->queues) {
> > > + xenbus_dev_fatal(dev, -ENOMEM,
> > > + "allocating queues");
> > > + return;
> > >
> >
> > I didn't use goto err, because another error handling is not required
> >
>
> It's recommended in kernel coding style to use "goto" style error
> handling. I personally prefer that to arbitrary return in function body,
> too.
>
> It's not a matter of whether another error handling is required or not,
> it's about cleaner code that is easy to reason about and consistent
> coding style.
>
> The existing code is not perfect, but that doesn't mean we should follow
> bad example.
And to be clear, I don't want to block this patch just because of this
coding style thing. It's still an improvement and fix a real problem.
So:
Acked-by: Wei Liu <wei.liu2@citrix.com>
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [Xen-devel] [PATCH] xen-netback: correctly check failed allocation
2015-10-16 9:05 ` Wei Liu
2015-10-16 9:28 ` Wei Liu
2015-10-16 9:28 ` Wei Liu
@ 2015-10-16 9:40 ` David Vrabel
2015-10-16 12:48 ` Insu Yun
2015-10-16 9:40 ` David Vrabel
3 siblings, 1 reply; 11+ messages in thread
From: David Vrabel @ 2015-10-16 9:40 UTC (permalink / raw)
To: Wei Liu, Insu Yun
Cc: Yeongjin Jang, Taesoo Kim, Ian Campbell, netdev, Yun, Insu,
linux-kernel, xen-devel
On 16/10/15 10:05, Wei Liu wrote:
> On Thu, Oct 15, 2015 at 02:02:47PM -0400, Insu Yun wrote:
>> I changed patch with valid format.
>>
>> On Thu, Oct 15, 2015 at 2:02 PM, Insu Yun <wuninsu@gmail.com> wrote:
>>
>>> Since vzalloc can be failed in memory pressure,
>>> writes -ENOMEM to xenstore to indicate error.
>>>
>>> Signed-off-by: Insu Yun <wuninsu@gmail.com>
>>> ---
>>> drivers/net/xen-netback/xenbus.c | 6 ++++++
>>> 1 file changed, 6 insertions(+)
>>>
>>> diff --git a/drivers/net/xen-netback/xenbus.c
>>> b/drivers/net/xen-netback/xenbus.c
>>> index 929a6e7..56ebd82 100644
>>> --- a/drivers/net/xen-netback/xenbus.c
>>> +++ b/drivers/net/xen-netback/xenbus.c
>>> @@ -788,6 +788,12 @@ static void connect(struct backend_info *be)
>>> /* Use the number of queues requested by the frontend */
>>> be->vif->queues = vzalloc(requested_num_queues *
>>> sizeof(struct xenvif_queue));
>>> + if (!be->vif->queues) {
>>> + xenbus_dev_fatal(dev, -ENOMEM,
>>> + "allocating queues");
>>> + return;
>>>
>>
>> I didn't use goto err, because another error handling is not required
>>
>
> It's recommended in kernel coding style to use "goto" style error
> handling. I personally prefer that to arbitrary return in function body,
> too.
>
> It's not a matter of whether another error handling is required or not,
> it's about cleaner code that is easy to reason about and consistent
> coding style.
Using xenbus_dev_fatal(); return; throughout would be consistent and
easy to reason about.
Also, the goto err path should raise a fatal error (instead of
disconnecting). I also note that failures in the xen_net_read_rate(),
xen_register_watchers() and read_xenbus_vif_flags() are also not handled.
David
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [PATCH] xen-netback: correctly check failed allocation
2015-10-16 9:40 ` [Xen-devel] " David Vrabel
@ 2015-10-16 12:48 ` Insu Yun
0 siblings, 0 replies; 11+ messages in thread
From: Insu Yun @ 2015-10-16 12:48 UTC (permalink / raw)
To: David Vrabel
Cc: Yeongjin Jang, Taesoo Kim, Wei Liu, Ian Campbell, netdev,
Yun, Insu, LKML, xen-devel
[-- Attachment #1.1: Type: text/plain, Size: 2195 bytes --]
For me, it seems more consistent using xen_bus_dev_fatal(); return;
Because other codes also use them.
If you want to use goto, then feel free to make a patch for this issue.
On Fri, Oct 16, 2015 at 5:40 AM, David Vrabel <david.vrabel@citrix.com>
wrote:
> On 16/10/15 10:05, Wei Liu wrote:
> > On Thu, Oct 15, 2015 at 02:02:47PM -0400, Insu Yun wrote:
> >> I changed patch with valid format.
> >>
> >> On Thu, Oct 15, 2015 at 2:02 PM, Insu Yun <wuninsu@gmail.com> wrote:
> >>
> >>> Since vzalloc can be failed in memory pressure,
> >>> writes -ENOMEM to xenstore to indicate error.
> >>>
> >>> Signed-off-by: Insu Yun <wuninsu@gmail.com>
> >>> ---
> >>> drivers/net/xen-netback/xenbus.c | 6 ++++++
> >>> 1 file changed, 6 insertions(+)
> >>>
> >>> diff --git a/drivers/net/xen-netback/xenbus.c
> >>> b/drivers/net/xen-netback/xenbus.c
> >>> index 929a6e7..56ebd82 100644
> >>> --- a/drivers/net/xen-netback/xenbus.c
> >>> +++ b/drivers/net/xen-netback/xenbus.c
> >>> @@ -788,6 +788,12 @@ static void connect(struct backend_info *be)
> >>> /* Use the number of queues requested by the frontend */
> >>> be->vif->queues = vzalloc(requested_num_queues *
> >>> sizeof(struct xenvif_queue));
> >>> + if (!be->vif->queues) {
> >>> + xenbus_dev_fatal(dev, -ENOMEM,
> >>> + "allocating queues");
> >>> + return;
> >>>
> >>
> >> I didn't use goto err, because another error handling is not required
> >>
> >
> > It's recommended in kernel coding style to use "goto" style error
> > handling. I personally prefer that to arbitrary return in function body,
> > too.
> >
> > It's not a matter of whether another error handling is required or not,
> > it's about cleaner code that is easy to reason about and consistent
> > coding style.
>
> Using xenbus_dev_fatal(); return; throughout would be consistent and
> easy to reason about.
>
> Also, the goto err path should raise a fatal error (instead of
> disconnecting). I also note that failures in the xen_net_read_rate(),
> xen_register_watchers() and read_xenbus_vif_flags() are also not handled.
>
> David
>
--
Regards
Insu Yun
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^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH] xen-netback: correctly check failed allocation
2015-10-16 9:05 ` Wei Liu
` (2 preceding siblings ...)
2015-10-16 9:40 ` [Xen-devel] " David Vrabel
@ 2015-10-16 9:40 ` David Vrabel
3 siblings, 0 replies; 11+ messages in thread
From: David Vrabel @ 2015-10-16 9:40 UTC (permalink / raw)
To: Wei Liu, Insu Yun
Cc: Yeongjin Jang, Taesoo Kim, Ian Campbell, netdev, Yun, Insu,
linux-kernel, xen-devel
On 16/10/15 10:05, Wei Liu wrote:
> On Thu, Oct 15, 2015 at 02:02:47PM -0400, Insu Yun wrote:
>> I changed patch with valid format.
>>
>> On Thu, Oct 15, 2015 at 2:02 PM, Insu Yun <wuninsu@gmail.com> wrote:
>>
>>> Since vzalloc can be failed in memory pressure,
>>> writes -ENOMEM to xenstore to indicate error.
>>>
>>> Signed-off-by: Insu Yun <wuninsu@gmail.com>
>>> ---
>>> drivers/net/xen-netback/xenbus.c | 6 ++++++
>>> 1 file changed, 6 insertions(+)
>>>
>>> diff --git a/drivers/net/xen-netback/xenbus.c
>>> b/drivers/net/xen-netback/xenbus.c
>>> index 929a6e7..56ebd82 100644
>>> --- a/drivers/net/xen-netback/xenbus.c
>>> +++ b/drivers/net/xen-netback/xenbus.c
>>> @@ -788,6 +788,12 @@ static void connect(struct backend_info *be)
>>> /* Use the number of queues requested by the frontend */
>>> be->vif->queues = vzalloc(requested_num_queues *
>>> sizeof(struct xenvif_queue));
>>> + if (!be->vif->queues) {
>>> + xenbus_dev_fatal(dev, -ENOMEM,
>>> + "allocating queues");
>>> + return;
>>>
>>
>> I didn't use goto err, because another error handling is not required
>>
>
> It's recommended in kernel coding style to use "goto" style error
> handling. I personally prefer that to arbitrary return in function body,
> too.
>
> It's not a matter of whether another error handling is required or not,
> it's about cleaner code that is easy to reason about and consistent
> coding style.
Using xenbus_dev_fatal(); return; throughout would be consistent and
easy to reason about.
Also, the goto err path should raise a fatal error (instead of
disconnecting). I also note that failures in the xen_net_read_rate(),
xen_register_watchers() and read_xenbus_vif_flags() are also not handled.
David
^ permalink raw reply [flat|nested] 11+ messages in thread